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      1 /*	$NetBSD: busypage.c,v 1.8 2020/03/17 18:31:39 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2010 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND
     17  * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
     18  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
     23  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
     25  * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     26  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
     27  * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include <sys/cdefs.h>
     31 #if !defined(lint)
     32 __RCSID("$NetBSD: busypage.c,v 1.8 2020/03/17 18:31:39 ad Exp $");
     33 #endif /* !lint */
     34 
     35 #include <sys/param.h>
     36 #include <sys/condvar.h>
     37 #include <sys/kthread.h>
     38 #include <sys/mutex.h>
     39 #include <sys/proc.h>
     40 
     41 #include <uvm/uvm.h>
     42 
     43 #include "kernspace.h"
     44 
     45 static struct uvm_object *uobj;
     46 static struct vm_page *testpg;
     47 static kcondvar_t tcv;
     48 
     49 static bool threadrun = false;
     50 
     51 static void
     52 thread(void *arg)
     53 {
     54 
     55 	mutex_enter(&testpg->interlock);
     56 	threadrun = true;
     57 	cv_signal(&tcv);
     58 	mutex_exit(&testpg->interlock);
     59 
     60 	rw_enter(uobj->vmobjlock, RW_READER);
     61 	uvm_pagewait(testpg, uobj->vmobjlock, "tw");
     62 
     63 	kthread_exit(0);
     64 }
     65 
     66 void
     67 rumptest_busypage()
     68 {
     69 	struct lwp *newl;
     70 	int rv;
     71 
     72 	cv_init(&tcv, "napina");
     73 
     74 	uobj = uao_create(1, 0);
     75 	rw_enter(uobj->vmobjlock, RW_WRITER);
     76 	testpg = uvm_pagealloc(uobj, 0, NULL, 0);
     77 	rw_exit(uobj->vmobjlock);
     78 	if (testpg == NULL)
     79 		panic("couldn't create vm page");
     80 
     81 	rv = kthread_create(PRI_NONE, KTHREAD_MUSTJOIN | KTHREAD_MPSAFE, NULL,
     82 	    thread, NULL, &newl, "jointest");
     83 	if (rv)
     84 		panic("thread creation failed: %d", rv);
     85 
     86 	kpause("lolgic", false, mstohz(100), NULL);
     87 
     88 	mutex_enter(&testpg->interlock);
     89 	while (!threadrun)
     90 		cv_wait(&tcv, &testpg->interlock);
     91 	mutex_exit(&testpg->interlock);
     92 
     93 	rw_enter(uobj->vmobjlock, RW_WRITER);
     94 	uvm_page_unbusy(&testpg, 1);
     95 	rw_exit(uobj->vmobjlock);
     96 
     97 	rv = kthread_join(newl);
     98 	if (rv)
     99 		panic("thread join failed: %d", rv);
    100 
    101 }
    102